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The TRF-3 Fourth Panel held that a bad faith litigation fine for AI-fabricated law and case citations must fall on the party, not on the lawyer who filed it.
Every court in the world is working out what to do when a lawyer files invented authority. This panel agreed the conduct was bad faith and then took the fine off the lawyer anyway, for a reason that has nothing to do with AI.
Bottom line: Binding between the parties. The Fourth Panel unanimously gave partial relief on internal appeal: the fine stands at 5 percent of the value of the principal claim, but it is now owed by the appellant party rather than by the lawyer who signed the petition.
Who this affects: Brazilian litigators and their clients, in-house counsel who instruct Brazilian firms, and professional liability underwriters. The reasoning is Brazilian procedural law, not a general AI rule.
Issue date: The copy obtained does not carry a judgment or publication date on its face. The court file is Agravo de Instrumento no 5013085-69.2025.4.03.0000.
What changed: The court separated two questions that most AI sanction decisions run together: whether filing fabricated authority is bad faith, and who pays for it.
Analysis: The client pays for the lawyer's fabricated citations and then has to sue the lawyer to recover. One judge proposed exactly that right of recourse plus an OAB referral in a separate vote declaration, which is where the lawyer's actual exposure lives, though the panel's dispositive stops at excluding him from the fine.
Primary sources: Acordao, TRF-3 Quarta Turma, AI 5013085-69.2025.4.03.0000 (PDF)
- Instrument (EN)
- Judgment on internal appeal, Interlocutory Appeal no 5013085-69.2025.4.03.0000
- Authority
- Tribunal Regional Federal da 3a Regiao, Quarta Turma; Rapporteur Des. Fed. Monica Nobre
- Jurisdiction
- Brazil, federal courts of the 3rd Region (Sao Paulo and Mato Grosso do Sul)
- Status
- Decided unanimously; partial relief granted
- Bindingness
- Binding between the parties; persuasive on the panel's stated tese
- Issue date / next deadline
- Not stated on the copy obtained; no deadline set by the judgment
- Legislation cited
- CPC arts. 79, 80 and 81; Lei no 8.906/1994 arts. 32 and 34, XIV
- Penalty
- 5 percent of the value of the principal claim, payable by the appellant party (art. 81 CPC allows between 1 and 10 percent of the corrected value)
- Primary source
- https://debatejuridico.com.br/wp-content/uploads/2026/08/litigancia-de-mafe.pdf
How the filing went wrong
The appellant had not paid court costs within the period set by TRF-3 Resolution 138/2017. Asked to regularise, the lawyer filed a petition claiming an exemption from costs in appeals arising from mandado de seguranca proceedings, saying the exemption was a rule widely recognised because of the literal wording of the statute.
The petition then quoted article 7, I of Federal Law no 12.016/2009 in a version the rapporteur describes, in the judgment itself, as a surprise to the court. It also transcribed fictitious judgments of the Superior Tribunal de Justica and of TRF-3, one of them attributed to the rapporteur's own docket.
Ordered to identify the official source of the quoted law and case law, the lawyer instead filed a retraction and asked for a further fifteen business days to pay the costs, arguing that superior court case law permits correction of preparation costs where the error is excusable. The interlocutory appeal was then dismissed for non-payment and the signing lawyer was fined.
The bad faith holding
On the merits of the conduct, the panel was direct. Recognising the error and retracting only after being ordered to prove the accuracy of the cited law and case law does not remove responsibility for filing a pleading generated by an artificial intelligence tool without any human supervision. Inserting false content into a petition addressed to the court in order to escape payment of costs is bad faith litigation.
The rapporteur anchored that on a passage from Minister Francisco Falcao in RMS 77.436, to the effect that filing text produced by AI and reproduced indiscriminately without proper human verification demands serious consequences, because deliberately circulating incorrect or false information in judicial proceedings amounts to bad faith litigation, liable to procedural sanction and disciplinary penalty.
Why the lawyer did not pay
The panel then split the question. The procedural fine must be borne by the party who would have benefited from the content of the petition, not directly by counsel. The wording of articles 79 and 80 of the Civil Procedure Code does not authorise imposing it directly on the lawyer without a specific procedure.
Two STJ authorities carry that: REsp 2.084.507/MG, decided 24 November 2025, and AgInt no AREsp 1.722.332/MT from 2022. Both hold that bad faith penalties under articles 79 and 80 are addressed to the parties and cannot be extended to the lawyer who acted in the case, who may be held liable only in a separate action under article 32 of Law no 8.906/1994, the OAB Statute.
The amount survived. Article 81 of the CPC allows more than one percent and less than ten percent of the corrected value of the claim, so 5 percent is not excessive.
The concurrence is where the lawyer's risk sits
Des. Fed. Wilson Zauhy agreed with the rapporteur's reasoning and added two determinations: that the party be guaranteed a right of recourse against the lawyer under article 32 of the OAB Statute, and that the OAB be notified to investigate a disciplinary infraction under article 34, XIV of the Statute.
Read together with the majority, the outcome is not that the lawyer escaped. It is that the client pays first and then pursues the lawyer, while the professional consequence moves to the bar association rather than the court file.
The tese the panel stated
The judgment sets out three propositions. Bad faith penalties under the CPC must be applied to the party, and direct condemnation of the lawyer in the same proceedings is not appropriate. Filing a petition with fictitious content constitutes bad faith litigation. Retraction only after being ordered to prove the accuracy of the cited law and case law does not prevent the sanction.
None of the three mentions artificial intelligence. The tool appears in the reasoning as the mechanism of the failure, not as a category with its own rule, and the standard applied is the ordinary duty of verification.
What we did not verify
I opened and read the full six page acordao, including the report, the rapporteur's vote, the concurring vote of Des. Fed. Wilson Zauhy, the ementa with its stated tese, and the dispositive section recording the unanimous result.
The copy I read was hosted by a third party legal site and its header points to the TRF-3 document retrieval service. It carries no judgment date, no publication date and no case value, so I cannot state when it was decided or how much 5 percent amounts to in reais. I did not open RMS 77.436, REsp 2.084.507/MG, AgInt no AREsp 1.722.332/MT, Resolution 138/2017, or the underlying mandado de seguranca file, and I did not check for a further appeal.
I will not name the lawyer or the party, and I will not say which AI tool was used. The judgment refers only to a ferramenta de inteligencia artificial and does not identify it.
Two things travel from this decision. First, retracting after the court asks you to prove your citations is too late; the panel treated the timing of the retraction as part of the bad faith, not as mitigation. Second, procedural law decides who pays, and in Brazil that is the client, who is then left with a separate action against counsel, and with a bar referral that one member of the panel proposed in a separate vote declaration but that the panel's dispositive does not order. If you are the client, your protection is the engagement letter and the insurance behind it, not the sanctions rule.
Source File
https://debatejuridico.com.br/wp-content/uploads/2026/08/litigancia-de-mafe.pdf
Open the acordao PDF and confirm three things: that the dispositive gives partial relief to exclude the condemnation of the lawyer who signed petition ID 327214571 and condemns the appellant party to a 5 percent fine, that the ementa's tese states bad faith penalties are directed at the party, and that the Zauhy concurrence adds a right of recourse against the lawyer plus an OAB referral under article 34, XIV.
A multa processual deve ser suportada pela parte que se beneficiaria do conteudo da peticao, e nao diretamente por seu patrono. A redacao dos artigos 79 e 80 do CPC nao autoriza a imposicao direta ao advogado, sem o devido procedimento especifico. ยท Des. Fed. Monica Nobre, rapporteur, TRF-3 Quarta Turma, AI 5013085-69.2025.4.03.0000
FAQ
Did the court excuse the fabricated citations?
No. It held that filing a pleading with text generated by an AI tool without human supervision, and only retracting after being ordered to prove the sources, constitutes bad faith litigation. It upheld both the finding and the 5 percent amount. It changed only who owes the money.
Can a Brazilian court ever fine the lawyer directly?
Not under articles 79 to 81 of the CPC in the same proceedings, on the authority the panel relied on. The route is a separate action under article 32 of the OAB Statute, plus disciplinary proceedings before the bar.
What happens to the client who now owes the fine?
In a separate declaracao de voto, Des. Fed. Wilson Zauhy proposed two further determinations: a right of recourse for the party against the lawyer under article 32 of the OAB Statute, and notification of the OAB to investigate a disciplinary infraction under article 34, XIV. Those additions appear only in his vote declaration; the panel's dispositive orders neither. The client's remedy is a separate claim, not relief in this file.
Does the judgment create a rule about AI in filings?
The stated tese does not mention AI. It states that bad faith penalties go to the party, that fictitious content in a petition is bad faith, and that late retraction does not prevent sanction. The AI tool is treated as how the failure happened, under the ordinary duty to verify what you file.
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